Graffiti is unsightly and is impossible to remove if it is not paint based but etched into perspex. Usually the whole perspex piece would have to be removed and replaced which is costly.
To prevent such vandalising, a new graffiti alarm system has just been patented. Invented by Seng Chu Tan and his team at Curtin University of Technology in Perth, Australia, the graffiti alarm system detects the noise of someone etching via the microphones on the surface of the material. The microphones are connected to a computer which can identify the correct sounds of someone carving rather than background noise.
An alarm then sounds and authorities are also notified.
Of course, if you LIKE graffiti, we've got many inspiring pieces of work to show you how to do it: